1. Field of the Invention
This invention relates generally to packaging of explosive materials and, more particularly, to the safe packaging of pyrotechnic materials which are extremely hazardous to work with.
2. Description of the Prior Art
The present invention has been developed as a way of reducing the hazard of mass producing practice rounds for a particular anti-armor missile in a production line facility. The missile in question is designed to be fired from a shoulder-held launcher, somewhat in the nature of the bazooka of World War II. The missile is packaged with the launcher, and the launcher is designed to be discarded after a single use. As developed, the missile and launcher combination is extremely effective when used by trained personnel.
Naturally, however, the actual missiles are too costly to be used in providing effective training of troops, since the training requires the firing of a substantial number of rounds before a soldier can become proficient in use of the weapon. For training purposes, a sub-caliber round is used which is launched from a cylinder equivalent to the standard missile launcher and which carries a pyrotechnic charge which produces a flash and explosion upon impact. Thus, the training round simulates the trajectory and effect of use of the real missile, thereby enabling the training of troops to become proficient in use of the weapon at a fraction of the cost which would be involved if the actual missiles were used.
For use in the training of troops, many thousands of training round launchers are required and the sub-caliber rounds are needed in the millions. This calls for a production line facility to manufacture them. However, the nature of the pyrotechnic materials employed in the training rounds is such that it is essential to provide off-line loading of the materials to form the pyrotechnic charge. The pyrotechnic charge, which may comprise a plurality of different ingredients, must be placed in the training round during production. The ingredients have an extremely low flash point and are very sensitive to heat or static charge developed from the frictional movement of the particles. It is desirable to restrict the particle movement to minimize the hazard of explosion from this source, particularly during handling on the manufacturing assembly line. Furthermore, it is desirable to be able to prepare the pyrotechnic charge in a facility away from the production line where the sub-caliber rounds are being assembled and manufactured so that the pyrotechnic materials can be handled in small quantities, thus reducing the hazard of a manufacturing plant explosion if a mishap does occur.
The loading of training rounds with pyrotechnic materials in conventional fashion is so hazardous that few, if any, of the known pyrotechnic manufacturing plants are willing to undertake the project. In one instance, a three-part pyrotechnic compound is employed and the conventional production technique is to drop the ingredients into the semi-manufactured training round, after which the round and contents are vibrated to produce the desired mixing of ingredients. With the materials needed for this purpose, this is extremely hazardous.
Known prior art techniques and apparatus provide very little assistance in attempting to solve this problem. The packaging of gun powder in bags, particularly for use with large-caliber guns, has been a common practice for many years. Indeed, this practice is employed at the present time with large naval guns, where the projectile is loaded into the barrel first, followed by the placing of a selected number of bags of powder into the firing chamber before the breach is closed. This permits the amount of powder used for a given firing of the gun to be tailored to the type of round, the distance to the target, etc. Thus, examples of the use of bags of various types for containing powder in, or in conjunction with, rounds for guns may be found in U.S. Pat. Nos. 777,319 of Ulrich, 797,218 of Du Pont, 2,353,934 of Schreib, 2,410,435 of Evans, Jr., 2,432,706 of Anderson et al, 3,276,378 of Gahle, and 3,771,459 of Lohnstein. Most of these involve cloth bags of various types and configurations, some having particular facility for ease in filling or for special purposes related to the use of the guns. Bourdelles, in U.S. Pat. No. 958,990, discloses the use of blocks of powder as a means of propulsion for a submarine torpedo, the blocks being maintained in the fabricated form by virtue of their being encased in a sheath of rubber stretched around the powder. The Schreib patent discloses the use of a cellophane bag which, after filling with the powder or other explosive mixture, has its mouth portion wrapped closed and stuck together. This device is said to have the capability of protecting its contents against the ingress of moisture, thus lessening the effects of moisture on the powder, and also of serving as a coating to the interior of the shell in which the bag is installed and providing a means for preventing frictional movement of the powder in the shell.
Other arrangements for encasing the contents of a shell are disclosed in U.S. Pat. Nos. 931,723 of Bird, 3,179,051 of Morse, and 3,399,622 of Houdek. The arrangements of Bird and Morse actually relate to a case for the shot of a shotgun shell, rather than for the powder. The casing of Houdek is designed for insertion within a shotgun shell in order to make the shell reloadable.
None of these examples of the prior art are considered suitable solutions to the problem to which the present invention is directed.